Forum text parsing problem.
 

On my install of vBulletin, the specific text phrase 'help' is being omitted from all posts and generated html. how is this possible? i.e., A message entered in formus ' help.. this is a test. help' will be displayed as message text ' this is a test.' This problem exists throughout entire install, does NOT affect admin control panel

UPDATE: New post/thread notification message contained ALL text actually entered, i.e.,

Here is the message that has just been posted:
***************
help.. this is a test. help
***************

please advise